Oil well filter



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Patented Sept. 5, 1944 olL WELL FILTER Harrison H. Holmes, Woodbury, N. J., and lWalter E. Lawson, Wilmington, Del., 'assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware Original application October 22, 1941, Serial No. 416,020. Divided and this application July 21, f 1942, Serial N0. 451,720

1 Claim. (Cl. 166-1) The present invention relates to the art of petroleum production, and in particular to a process for forming'oil well filters of porous cement.

This application is a. division of Serial No. 416,020, filed October 22, 1941.

Contrary to expectation, the problem of forming such a lter in place from porous cement diiers markedly from that vof preparing gravel pack lters or the like. VAThis difference is due to certain peculiar properties of. the porous cement grout prior to setting. `For instance it is characteristic of this material that it cannot be set under water. Furthermore, it must be kept out of contact with Water prior to reaching its ultimate position in the well. This is necessary to prevent flushing of the cement in the grout from the pore-forming aggregate therein.

The invention may be appreciated more readv ily by referring to the attached drawing. n

Figure 1 is a side view in cross-section of the well with the drillable liner and attached dump bailer pla-ced in position at vthe bottom of the well. Figure 2 is a similar view of the' same elements in diilerent arrangement. Figure 3 is a side view partly in cross-section and partly in perspective of the same elements after the bailer is pulled away from the liner. Figure 4 is a sectional viewon the line 4-4 of Figure 1.

Similar numerals refer to similar parts throughout the several views. 4

The sides of the Well are dened by the casing I, below whichvis the borehole 3. Referring to Figures 1 `and 4, at the bottoml of the well 1 is disposed the section of drillable liner 2 which Contact with Water `is to be avoided, especially y with respect to porous cement grouts containing included oil or other oleaginous ingredients as disclosed and claimed in copending application Serial No. 309,899, filed December18, 1939.

These and other diiiiculties necessitate the development of special methods and equipment for forming oil well filters from lporous cement.

The object of the present invention is a new ,and-improved arrangement for forming porous with means for tripping after the liner is down and disposed in its iinal location. The centering devices must be made so that they will not cause bridging. The liner is rclosed at the top is joined by means of telescope joint I3 and shear pins 'I4 to the dump bailer 9 of special design containing the porous cement grout 8. The drillable liner 2 and attached bailer 9 are maintained in position by centering fingers 5 attached' to the drillable liner and engaging the wall of the -borehole. Slots 'II in the side of the bailer are closed by the sleeve valve closure I2. The umbrella device I5 is disposed in the region of the conical end I6 to prevent oating. The `conventional I tripping device I0, which as illustrated in Figure with any convenient drillable. plug, preferably ment. If a steady flow of Water is encountered 1 it may be desirable to fill the well withv oil after bailing out the water present so that the weight of the column of oil will prevent entr ance of more water.

1 is a pair of cables attached to the top of sleeve I2 at points E and E, raises the sleeve I2 (as illus-- trated in Figure 2) and thus permits the cement grout 48 to ,flow out of slots II and about the` drillable liner 2. When the cement has set sufficiently to hold the liner in position, the bailer is pulled away '(as illustrated in Figure 3) by breaking the shear pins I4.

They method of operation is as follows: With the slots II closed by sleeve I2 as shown in Figure l, the dump bailer which is attached to the drillable liner 2 as illustrated in Figure 1 is lled with porous `cement grout 8, and the ensemble is lowered by means of lowering cable I'I to the bottom' of the Well; centering fingers 5 following downward and engaging the wall of the borehole 3. When the liner and attached bailer are in position at-the bottom of the well as illustrated in Figure 1, the sleeve I2 is raisedby means of thel tripping device I0 andthe cement grout 8 ows through the slots II down and about the drillable liner 2, as illustrated in Figure 2. When the/cement has set suiiiciently to hold the liner in position the bailer!! is raised by means of cable I'I, breaking the shear pins I4. There is thus and surrounded by 'porous concrete 20.

The liner may be drilled out or otherwise removed to leave a porous cement filter with pumping cavity.

This invention is characterized by the advantage that it permits a facile and efcient arrangement for forming porous cement oil Well filters.

In addition to the foregoing embodiment it will be appreciated that many variations of the same may be devised within the scope of the present invention as described. For instance, although we have spoken of a drillable liner in the foregoing, the invention is applicable as well to any type of removable liner including one that can be dissolved or broken down by other chemical means, as described in our copendng applica.

tion Serial N0. 416,020, filed October 22, 1941.

sure for said slot and a tripping device adapted v to raise said sleeve to dump cement, whereby i porous cement grout may be poured about said liner and the bailer may be severed from the liner by breaking the shear pins after the cement sets, holding the liner in position.

HARRISON H. HOLMES. WALTER E. LAWSON. 

